Despite the tremendous clinical success of vaccines and other approaches to modulating immune responses, the complexity of some of the most pervasive diseases, autoimmune disorders and conditions such as allergic reactions continue to present formidable challenges. For example, the human immunodeficiency virus (HIV) is able to evade immune clearance by rapid mutation and concealment in the mucosa, and cancerous tissues actively suppress tumor-destructive immune cells. Likewise, the prevalence and toll of autoimmune diseases, such as multiple sclerosis, rheumatoid arthritis, lupus, type I diabetes, celiac disease, as well as a wide variety of allergic reactions, represent critical types of immune system challenges for which improved compositions and methods are needed. An obstacle to achieving this goal is the complex composition (e.g., carriers, excipients, adjuvants, antigens) that makes characterizing and testing the multitude of new vaccine and other immune-modulatory candidates empirical and economically infeasible. Moreover, while numerous biomaterials have been explored to improve adjuvant and other immune-modulatory performance through controlled release, co-delivery of multiple cargoes, and targeting to sites such as lymph nodes, recent studies have led to a revelation that many ubiquitous polymeric vaccine carriers activate inflammatory pathways even in the absence of other antigens or adjuvants. Examples of both degradable and non-degradable materials have been reported in this context, including poly(lactide-co-glycolide), poly(styrene), chitosan, and hyaluronic acid. (See, for example, Sharp, F. et al. Proceedings of the National Academy of Sciences of the United States of America 2009, 106 (3), 870-5; Demento, S. L. et al. Vaccine 2009, 27 (23), 3013-21; Da Silva, C. A. et al. J Immunol 2009, 182 (6), 3573-82; and Termeer, C. et al. J Exp Med 2002, 195 (1), 99-111). Thus, while polymeric materials offer great potential for new vaccines, the intrinsic immune characteristics can hinder rational vaccine design and translation because the role of the carrier itself may alter how other components or signals (e.g., antigens, adjuvants) are processed. Thus, there is a need for improved compositions and methods that avoid the unintended effects of carriers, and yet can be tuned for providing a variety of effects on adaptive immunity, such as either stimulating an immune response that is specific for a particular antigen, or inducing tolerance to it. The present disclosure is pertinent to these needs.